Optoelectronic components which emit light can be for example light emitting diodes (LEDs) or organic light emitting diodes (OLEDs). An OLED may include an anode and a cathode with an organic functional layer system therebetween. The organic functional layer system may include one or a plurality of emitter layers in which electromagnetic radiation is generated, a charge generating layer structure composed of respectively two or more charge generating layers (CGL) for charge generation, and one or a plurality of electron blocking layers, also designated as hole transport layer(s) (HTL), and one or a plurality of hole blocking layers, also designated as electron transport layer(s) (ETL), in order to direct the current flow.
Optoelectronic assemblies include for example two or more optoelectronic components, for example LEDs and/or OLEDs, and drive circuits, for example drivers, for operating the optoelectronic components. The optoelectronic components can be electrically connected in parallel, for example. An optoelectronic component, for example an OLED, can be segmented and therefore include a plurality of OLED elements. The OLED elements can for example be electrically connected in parallel and/or share at least one common electrode. By way of example, two OLED elements include the same cathode, but have organic functional layer structures separated from one another and anodes correspondingly separated from one another. This can contribute to the fact that, in the case of a short circuit of one of the OLED elements, the other OLED elements can in principle continue to be operated.
Despite elaborate quality control procedures for OLEDs, the situation in which the OLEDs fail spontaneously in use cannot be completely ruled out. A typical fault pattern for spontaneous failures is short circuits between the electrodes. Such short circuits are generally over a small area; a large part of the total current is thus concentrated at this short-circuit point. Consequently, the current density is significantly boosted, as a result of which these locations can heat up to a very great extent depending on the areal embodiment. This can lead to the melting of the electrodes, to dark spots in the luminous image, to completely dark OLEDs and/or simply to locations becoming very hot on the OLED. In order to prevent potential hazards as a result of this overheating (combustion hazard, fire, rupture) such a short circuit should be detected by the drive or driver electronics or a subordinate evaluation unit and/or computing unit and a corresponding reaction, for example a protection measure, should be implemented (switching off of the short-circuited component, generation of warning signals, bypassing, that is to say circumvention of the short circuit, etc.). Precisely in the automotive sector, the manufacturers demand that for example defective OLEDs or LEDs in rear lights must be electronically detected and at least reported to the on-board system.
For detecting a short circuit during the operation of an OLED, which can occur in individual components of the OLED, conventional fuses are known, the functional principle of which is based, inter alia, on the current flowing via the short circuit and the voltage change associated therewith.
During the operation of the OLED it is furthermore possible for a local defect to occur which locally increases the conductivity between anode and cathode of the OLED, without a complete short circuit being generated in the process. To put it another way, here a so-called conditional short circuit is generated in which a voltage dropped across the short circuit is not reduced to a completely negligible measure. A conventional fuse interconnected with the OLED affords no protection against this since, in the conditional short circuit, the voltage dropped across the OLED does not decrease or the total current flowing through the OLED does not necessarily increase. Therefore, the total resistance of the OLED does not change. With external voltage remaining the same and external current remaining the same, a localization and/or concentration of the current in the local defect occurs. In a case of a conditional short circuit of an OLED, a conventional fuse accordingly does not necessarily lead to an interruption of the operation of the OLED.
In the case of a conditional short circuit, the majority of the current disadvantageously flows through the local defect, as a result of which the local current density increases. This can disadvantageously lead to a local overheating at the relevant location of the local defect. An injury hazard, such as, for example, a combustion hazard upon direct contact with the OLED, and a fire hazard which are based on the local overheating of the OLED can occur here, even with the use of a conventional fuse as described above.